The rotational motions of different biopolymer moieties and the lateral motions of phospholipids in membranes are being studied using nuclear magnetic resonance relaxation techniques, primarily variants of an experiment related to spin-lattice relaxation in the rotating frame (T1 rho). There are unique properties of the experimental techniques we have developed which make it possible to study biopolymer and membrane dynamics more readily. This should enable us to begin to form a more realistic dynamic picture of proteins and membranes as an extension of the static picture of biopolymers which is emerging from many X-ray crystallography laboratories. We will examine the C-2 proton resonance of the four histidine residues of ribonuclease using a new off-resonance T1 rho off technique as inhibitor is added to discover any differential effects such binding may have on the motional freedom of different protein moieties. The same resonances will be monitored as the protein is unfolded in a study of the pathway of protein (un)folding. A more sophisticated mathematical model relating NMR relaxation parameters to the overall tumbling motion and internal motions in biopolymers will be developed. Molecular motions in polynucleotides and nucleic acids will be investigated. Studies of lateral diffusion, as a quantitative parameter for membrane "fluidity", will be continued and extended to include the effect of phospholipid head group on lateral mobility and the influence of a constituent protein on phospholipid mobility via examination of the retinal rod outer segment membrane.